With increasing integration of semiconductor devices, there may be a heightened need to form finer patterns of subquarter micron capacity in photolithography processes. A photolitography technology has been proposed which may use an ArF excimer laser (e.g., .lambda.=193 nm) for devices beyond the 1 giga capacity. This technology may be intended to replace conventional KrF excimer lasers using deep ultraviolet rays (e.g., .lambda.=248 nm). Accordingly, it may be desirable to develop new chemically amplified resist compositions.
In general, the prerequisites for chemically amplified resist compositions for use with an ArF excimer laser may be as follows:
(1) transmittance in the range of 193 nm; PA1 (2) excellent thermal characteristics, such as for example, high glass transition temperature (T.sub.g); PA1 (3) excellent adhesion to film materials; PA1 (4) excellent resistance against a dry etching process; and PA1 (5) capability of being developed using a conventional developer.
An example of one polymer which has been developed to possibly posses the above properties is a tetrapolymer, namely poly (IBMA-MMA-tBMA-MAA) which is represented by the general formula: ##STR3##
The above tetrapolymer may not be satisfactory. In particular, the tetrapolymer may have a very weak resistance against an etching process and may have weak adhesive properties. Additionally, a special developer may be needed for the development of the tetrapolymer. To potentially address the above problems, a class of cyclopolymers have been proposed which are of the general formula: ##STR4##
These cyclopolymers, however, also potentially suffer from drawbacks. Specifically, the cyclopolymers may have weak adhesive properties, and as a result lifting may possibly occur at the resist. Moreover, a special developer which may require separate preparation and may have to be employed in a specific concentration range might have to be used with the above cyclopolymers in place of generally accepted developers.